After the introduction of a Haemophilus Influenzae type b (Hib) conjugate vaccine into The Gambia, the annual incidence of Hib meningitis has fallen from more than 200 per 100,000 before vaccination to 21 per 100,000 during the past 12 months.
PIP: This paper reports on the impact of Haemophilus influenzae type b (Hib) conjugate vaccine on the incidence of Hib meningitis in Gambia. The incidence of Hib meningitis among infants younger than 12 months of age in Gambia is greater, and the children affected are younger, compared to children in more developed countries. Between March 1993 and December 1995, children who were administered diphtheria-tetanus-pertussis (DTP) vaccination were randomly assigned a course of Hib conjugate vaccine mixed with DTP or DTP only. In Gambia, DTP vaccinations are recommended at 2, 3, and 4 months of age. The coverage of these vaccinations has been over 85% since 1990. Hib disease has not disappeared from Gambia in the last 2 years since the national immunization program was introduced. However, the incidence rate has declined rapidly, and a longer period of vaccination may be needed to achieve a sufficient herd effect to protect unimmunized children.